Support for Verilog comments.
Both Verilog-2005 and SystemVerilog-2012 support two forms of
comments. Single-line comments that start with // and end with a newline.
Multi-line comments start with /* and end with */.
Many lexers would skip past comments (and whitespace). We instead create
:vl-comment tokens. This is generally meant to allow us to preserve
comments as we process and pretty-print the source code.
See also the comments in preprocessor-ifdef-minutia regarding line
continuations and comments in macro text.
- Try to match a /* ... */ style comment.
- Try to match a // ... style comment.